Grab Ring

Abstract: The disclosure relates to a grab ring comprising an annular element (10) having one set of teeth (13) projecting outwardly at an inclined angle to the annular element to one side thereof and a second set of teeth (14) projecting inwardly at an inclined angle to the annular element to the other side thereof to engage between a pair of inner and outer concentric cylindrical surfaces (20,24) to permit relative movement between the surfaces in one direction whilst preventing relative movement in the opposite direction.

Description: The invention relates to grab rings. Grab rings are commonly used in a wide variety of applications where it is required to couple cylindrical components in a bore of another component. A grab ring is mounted on the components and has projecting teeth around its periphery angled to engage with a component, the teeth being arranged so that the cylindrical component can be engaged in the bore in one direction but not extracted. Grab rings having inclined teeth projecting outwardly and inwardly are disclosed in US patent 4073514. GB patent 1550624 shows a grab ring embodied in a sealing member. This invention provides a grab ring comprising an annular element having one set of teeth projecting outwardly at an inclined angle to the annular element to one side thereof and a second set of teeth projecting inwardly at an inclined angle to the annular element to the other side thereof to engage between a pair of inner and outer concentric cylindrical surfaces to permit relative movement between the surfaces in one direction whilst preventing relative movement in the opposite direction; wherein the ring is embodied in a resilient sleeve midway along the sleeve with one set of teeth projecting outwardly of the sleeve and the other set of teeth projecting inwardly of the sleeve, the outer periphery of the sleeve having annular sealing ribs to one side of said one set of teeth on the grab ring and the inner periphery of the sleeve having inner sealing ribs on the opposite side of the other set of teeth on the grab ring. Preferably the sleeve is a thick walled resilient stepped sleeve having a larger diameter portion on one side of the grab ring and a smaller diameter portion on the other side of the grab ring, the larger diameter portion extending partway up the outer teeth and the smaller diameter portion extending part way up the inner teeth. The teeth may be of generally rectangular shape or have radial edges. In any of the above arrangements, a multiplicity of teeth may be provided at spaced locations around said edges of the annular element. In the latter arrangement, the teeth may be located in pairs directly opposite one another around the edges of the annular element. The invention also provides a grab ring comprising an annular element having one set of teeth projecting outwardly at an inclined angle to the annular element to one side thereof and a second set of teeth projecting inwardly at an inclined angle to the annular element to the other side thereof to engage between a pair of inner and outer concentric cylindrical surfaces to permit relative movement between the surfaces in one direction whilst preventing relative movement in the opposite direction; wherein said grab ring is embodied in an annular sealing element of circular cross-section with the ends of the teeth of the grab ring projecting from the radially inner and outer surfaces of the sealing element. The following is a description of some specific embodiments of the invention, reference being made to the accompanying drawings, in which: Figure 1 is an elevation view of a grab ring for locking an inner cylindrical component in an encircling cylindrical bore of another component; Figure 2 is a side view of the grab ring of Figure 1; Figure 3 shows a tube, the grab ring of Figure 1, a seal and a socket in alignment ready for assembly; Figure 4 shows the socket of Figure 3 with the seal and grab ring inserted ready to receive the tube; Figure 5 shows the socket of Figure 4 with the tube inserted; Figure 6 shows a similar assembly of tube and socket to that of Figures 3 to 5 in which the grab ring is embodied in the seal; Figures 7 and 8 show the arrangement of Figure 6 partially assembled and fully assembled respectively; Figure 9 is a section through part of a socket with two composite grab rings/seals disposed therein; Figure 10 is a section through a thick wall resilient sleeve embodying the grab ring in accordance with Figures 1 and 2; Figure 11 shows a tube, grab ring/sleeve in accordance with Figure 10 and socket in alignment ready for assembly; Figure 12 shows grab ring/sleeve assembled in the socket ready to receive the tube; Figure 13 shows the tube assembled in the socket; and Figures 14 to 16 are similar views to Figures 11 to 13 showing a different assembly sequence. Referring firstly to Figures 1 and 2 of the drawing, there is shown a grab ring formed in a hard spring steel and comprising a flat annular element 10 lying in a radial plane and having inner and outer edges 11, 12. The inner edge has a multiplicity of equi-spaced integral generally rectangular profile teeth 13 projecting inwardly and to one side of the plane of the annular element and the outer periphery 12 of the element has a corresponding set of integral generally rectangular teeth 14 formed opposite the teeth 13 and projecting outwardly to the other side of the element. The inner teeth 13 provide inwardly facing edges 15 to engage and bite into the surface of a component with the grab ring and the outer teeth 14 provide outwardly facing edges 16 to engage and bite into a surface encircling the grab ring. Preferably the side edges of the teeth extend radially of the annular element so that the teeth taper slightly towards their outer ends. The grab ring has a wide variety of applications and is particularly suitable for locking a tube in a coupling body with a seal if required to form a sealed joint. Such an arrangement is illustrated in Figure 3 to 5 which reference will now be made. A coupling body 17 has a throughway 18 which is open at one end 19 of the coupling body to receive an end part of a tube 20 to be fixed and sealed in the coupling body. The throughway 18 is of smaller diameter than the tube 20 and to accommodate the tube is increased in diameter of step 21 to a bore 22 in which the tube 20 is a close fit. The bore 22 is increased in diameter again at a step 23 adjacent the open end of the throughway to form an open socket 24. The socket receives an "O" ring seal 25 to seal between the socket and tube 20 and also the grab ring for locking the tube in the socket. The grab ring is dimensioned so that the outer teeth bear against and bit into the surface of the socket 24 and the inner teeth bear against and bite into the surface of the tube 20. In Figure 4, the seal 25 has been inserted in the socket 24 against the step 23, and the grab ring is then offered up with the outer teeth of the ring inclined outwardly of the socket so that as the ring is inserted into the socket, the teeth can flex to allow a ring to enter the socket and in situ bite into the surface of the socket to retain the ring as shown in Figure 4. The inner teeth 13 of the grab ring are angled into the throughway to allow the tube 20 to be inserted through the grab ring into the bore 22 to engage the shoulder 21 as shown in Figure 5. When the tube is in place the teeth bite into the surface of the tube to hold it in place. The seal 25 is trapped between the grab ring and shoulder 23 and is thereby held in sealing engagement between the encircling surface of the socket, the shoulder 23 and the outer surface of the tube. Figures 6 to 8 of the drawings show the inventive arrangement in which the grab ring is embodied in the seal 25 with the annular element 10 of the ring disposed at the centre of the seal and the teeth 13, 14 projecting from the surface of the seal. The arrangement is otherwise similar to that of Figures 3 to 5. Figure 9 shows part of a socket for a coupling body in which two grab rings both embodied in resilient seals are mounted to receive and engage a tube. Figure 10 shows a further inventive arrangement in which a grab ring is embodied in a stepped thick walled resilient sleeve 35 having a larger diameter portion 36 to one side of the grab ring and the smaller diameter portion 37 to the other side. The larger diameter portion 36 extends partway up the outwardly projecting teeth 14 and is formed with a pair of encircling ribs 36a. The outwardly projecting teeth 14 of the grab ring are arranged to lock the grab ring/sleeve in a bore and the encircling ribs 36a form a seal with the bore. The smaller diameter portion 37 of the sleeve to the other side of the grab ring extends partway up the inwardly projected teeth of the grab ring and is formed with a pair of obliquely angled annular sealing elements 38 facing in the opposite direction to the teeth 30 to seal with a surface of a tube extending through the sleeve/grab ring assembly. Figure 11 of the drawings shows a coupling body and tube similar to that of Figures 3 to 5 referred to above with a sleeve/grab ring arrangement of Figure 10 for securing and sealing the tube in the coupling body. In Figure 12 the sleeve/grab ring assembly has been inserted in the socket 34 of the coupling body 17, the outwardly projecting teeth 14 holding the assembly in the socket and the encircling ribs 37 sealing with the surface of the socket. The tube 20 can then be inserted through the angled seals 38 around the inner periphery of the sleeve and through the teeth 13 of the grab ring into the bare 22 formed in the socket for the tube. The teeth 13 hold the tube against withdrawal and the seals 38 form a sealing engagement with the surface of the tube as can be seen in Figure 13. Figures 14 to 16 show a similar sequence in which the sleeve/grab ring is assembled on the tube 21 and the tube/sleeve assembly is inserted in the socket in the coupling body.

Claims: A grab ring comprising an annular element (10) having one set of teeth (14) projecting outwardly at an inclined angle to the annular element to one side thereof and a second set of teeth (13) projecting inwardly at an inclined angle to the annular element to the other side thereof to engage between a pair of inner and outer concentric cylindrical surfaces to permit relative movement between the surfaces in one direction whilst preventing relative movement in the opposite direction; characterised in that the ring is embodied in a resilient sleeve midway along the sleeve (30) with said one set of teeth (14) projecting outwardly of the sleeve and the other set of teeth (13) projecting inwardly of the sleeve, the outer periphery of the sleeve having annular sealing ribs (37) to one side of said one set of teeth on the grab ring and the inner periphery of the sleeve having inner sealing ribs (38) on the opposite side of the other set of teeth on the grab ring. A grab ring as claimed in claim 1, characterised in that the sleeve (35) is a thick walled resilient stepped sleeve having a larger diameter portion (36) on one side of the grab ring (10) and a smaller diameter portion (37) on the other side of the grab ring, the larger diameter portion extending partway up the outer teeth and the smaller diameter portion extending part way up the inner teeth. A grab ring as claimed in claim 1 or claim 2, characterised in that the teeth (13, 14) are of generally rectangular shape or have radial edges. A grab ring as claimed in any of claims 1 to 3, characterised in that a multiplicity of teeth (13, 14) are provided at spaced locations around said edges of the annular element (10). A grab ring as claimed in claim 4, characterised in that the teeth (13, 14) are located in pairs directly opposite one another around the edges of the annular element (10). A grab ring comprising an annular element (10) having one set of teeth (14) projecting outwardly at an inclined angle to the annular element to one side thereof and a second set of teeth (13) projecting inwardly at an inclined angle to the annular element to the other side thereof to engage between a pair of inner and outer concentric cylindrical surfaces to permit relative movement between the surfaces in one direction whilst preventing relative movement in the opposite direction; characterised in that said grab ring is embodied in an annular sealing element (25) of circular cross-section with the ends of the teeth (13, 14) of the grab ring projecting from the radially inner and outer surfaces of the sealing element.

Inventors: GUEST JOHN DEREK, GUEST, JOHN DEREK
Applicants: GUEST JOHN D, GUEST, JOHN DEREK
Application year: 1994
Main classification: F16L37
IPC codes: F16L37, F16B21